The Hubble Heritage image of NGC 3132 was constructed
from black-and-white Hubble Space Telescope data
obtained from the public
archive. The original observers used 5 different
filters to select wavelengths
of light corresponding to 5 different chemical
elements which are each sensitive to different physical
conditions within the nebula. Hence the 5 greyscale
images displayed on the left appear somewhat different
from each other. The Heritage Team assigned
the primary colors of light to 3 of these images
in order to construct the glowing image highlighted
as our November 1998 release.
In this case, color corresponds to excitation energy,
which depends on the temperature of the gas and
the amount of ultraviolet light from the hot star
in the center.

A different combination of 3
filters was used to construct the images on
the collage page, which
thus appear different from our final color image.
Can you tell which ones they were?

Nature displays a remarkable
economy of form as displayed on the left by
the striking similarity of Yellowstone's Grand Prismatic
Spring to the Hubble Heritage project's new rendering
of NGC 3132. Though the two physical systems are
completely different, the reasons for the similarity
of the images do share some common threads. In the
Grand Prismatic
Spring the colors are produced by different
species of thermophilic bacteria that live in narrow
temperature ranges as the waters of the hot spring
naturally cool farther from the source of the heated
water. The reddish bacteria at the outer edge survive
in the coolest water with the yellowish and greenish
bacteria living in progressively hotter water. The
water in the central blue area of the spring is
too hot to support any of the bacterial species.

The colors on the Heritage image of NGC 3132 are
similarly derived with different colors tracing
three different atomic species
in the planetary nebula. The reddish colors show
areas where singly ionized nitrogen emits, green
maps out areas where the H-alpha emission from hydrogen
occurs (yellow regions have both [N II] and H-alpha),
and blue traces emission from doubly ionized oxygen,
[O III]. The segregation of these species occurs
because each atomic species requires different levels
of ionizing radiation which decreases with distance
from the central star.